Illicit Trafficking Of Radioactive Materials Research Articles

Radionuclide identification based on energy-weighted algorithm and machine learning applied to a multi-array plastic scintillator

Radiation portal monitors (RPMs) installed at airports and harbors to prevent illicit trafficking of radioactive materials generally use large plastic scintillators. However, their energy resolution is poor and radionuclide identification is nearly unfeasible. In this study, to improve isotope identification, a RPM system based on a multi-array plastic scintillator and convolutional neural network (CNN) was evaluated by measuring the spectra of radioactive sources. A multi-array plastic scintillator comprising an assembly of 14 hexagonal scintillators was fabricated within an area of 50 × 100 cm2. The energy spectra of 137Cs, 60Co, 226Ra, and 4K (KCl) were measured at speeds of 10–30 km/h, respectively, and an energy-weighted algorithm was applied. For the CNN, 700 and 300 spectral images were used as training and testing images, respectively. Compared to the conventional plastic scintillator, the multi-arrayed detector showed a high collection probability of the optical photons generated inside. A Compton maximum peak was observed for four moving radiation sources, and the CNN-based classification results showed that at least 70% was discriminated. Under the speed condition, the spectral fluctuations were higher than those under dwelling condition. However, the machine learning results demonstrated that a considerably high level of nuclide discrimination was possible under source movement conditions.

Linear Regression and Machine Learning for Nuclear Forensics of Spent Fuel from Six Types of Nuclear Reactors

The illicit trafficking of radioactive materials, especially weapon-grade uranium or plutonium, is a significant security threat. Nuclear forensics helps trace the illicit trafficking of radioactive materials. The present study develops the methods for the forensics of the possible origins of fuels irradiated in nuclear reactors, which are the most powerful sources producing radioactive materials, including plutonium. Three key factors are significant for irradiated fuel forensics, namely, initial 235U enrichment, burnup, and the type of irradiation nuclear reactors. The methods for the first two are determined based on experimental data of six nuclear-reactor technologies and are further verified using the neutron-transport-depletion coupling simulation of the two major commercial reactor technologies, a pressurized-water reactor (PWR) and a boiling-water reactor (BWR). In addition, three machine-learning techniques are applied to discriminate between a PWR and a BWR, which are quite similar in neutronic properties, with nice accuracy and generalization ability. In summary, the presently determined methods provide a reliable pathway to predict the origins of spent nuclear fuels.3 MoreReceived 18 August 2022Revised 7 November 2022Accepted 1 February 2023DOI:https://doi.org/10.1103/PhysRevApplied.19.034028© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionNeutron physicsNuclear decayNuclear powerRadioactive wasteTheory, design & simulation of reactorsTechniquesNuclear data analysis & compilationNuclear PhysicsEnergy Science & Technology

SICURA: a new handheld radionuclide identification device with gamma and neutron response

SICURA is a two-year project that aims to develop a portable device to be employed in the prevention of illicit trafficking of radioactive material through γ and neutron detection. In order to be attractive to industries, efforts were made to fulfill the following characteristics: portability, good photon energy resolution and sensitivity in compliance with relevant international standards, sensitivity to neutrons with energies typical of the most common sources, fast response, low cost, user friendly interface. The SICURA system consists of two photon detectors for photon detection (CsI) and spectrometry (CZT) and a moderated Helium-3 counter for neutron detection. Dedicated analog and digital electronics readout have been developed, ensuring high energy resolution for accurate elements identification, signal digitization, alarm and information transmission to the end user.This paper describes the development of the SICURA device and the first results of its individual detectors characterizations.

Combating Illegal Movement of Radioactive Materials and Objects Across the State Border of Ukraine

This article, by using general scientific methods, presents the main issues and ways to improve the appropriate technical equipment of state border crossing points, legal responsibilities of the State Border Guard Service of Ukraine and the main results of operational activities to combat the illegal movement of radioactive materials and objects across the state border. The article shows the results of international cooperation and the implementation of international technical assistance projects by the State Border Guard Service of Ukraine on improving the system of prevention of illicit trafficking of radioactive materials and objects.
 Furthermore, the article examines the main responsibilities of the State Border Guard Service of Ukraine on ensuring radiation safety, which affects the real needs of equipping the state border guard bodies with the necessary technical tools. It is indicated that the detection of suspicious objects at state border crossing points may be limited to detection of exceeding the permissible radiation level without details about its kind with their further transfer to specially authorised state authorities of Ukraine for detailed examination.
 It is essential to note the need to improve the legal regulation of illegal trafficking of materials and objects that are hazardous radioactive sources across the state border considering negative economic and social consequences to the person, society, state and international community. There is an urgent need for well-defined regulation regarding the radiation materials and objects to prevent their movement across the state border without obtaining a special permit.
 Taking into account the need to reduce the budget expenditure of the border agency, this article provides recommendations to determine the purpose of the state re-equipment program of state border crossing points with modern tools for detection of radiation sources.

Nuclear Security Architecture & Radiological Disaster Response in India Progress and Challenges

The nuclear security architecture in India is three-fold: the infrastructure security including physical security of the nuclear plant; port and border security including training and capacity building to prevent any illicit trafficking of nuclear material into the country and; the inter-institutional coordination at the Centre and State level during radiological emergencies. However, there exist structural weaknesses that need to be accounted for in all these three areas. It is imperative to develop capacities not only for safe handling, transport and disposal of nuclear material but also instituting stringent cyber-security laws, border security measures and functional Centre-State coordination in crisis situation for the safety and security of the general population. The following paper seeks to address these challenges and provide recommendations for strengthening the nuclear security and disaster response framework in India. The paper draws recommendations from the 2019 IPCS workshop on Smuggling and Radiation Detection, on the illicit trafficking of radioactive materials supported by the Office of Nuclear Smuggling Detection and Deterrence (NSDD) of the United States Department of Energy (DOE).

Qualification of a compact neutron detector based on SiPM

Silicon Photomultipliers (SiPM) are photon sensors featuring high detection efficiency, single photon sensitivity and extended dynamic range; they represent a valuable solution for compact and lightweight hand-held instruments ideal for border control against the illicit trafficking of radioactive material or environmental measurements. This paper reports the results obtained with a standalone compact and modular system (I-spector) customized to detect fast neutrons with gamma discrimination capability. The system consists of 4 SiPM (6× 6 mm2 each) coupled to a fast neutron sensitive scintillating material (EJ-276). It includes an HV bias generator, an on-board digitizer and a microcontroller to perform real-time pulse shape analysis, ethernet and LORA connectivity. The measurements performed to define the specifications and to steer the design will be discussed, together with the results achieved by the prototype in response to a 252Cf source. The system has been shown to be linear up to 6 MeV achieving a neutron-gamma discrimination with a Figure of Merit (FoM) of 2.52 ± 0.09 in the energy window of 1–1.5 MeV together with a FoM larger than 1.27 down to 200–300 keV

PRE-ANTHROPIC AND PRESENT OUTDOOR GAMMA EQUIVALENT DOSE RATE OF THE HISTORIC CENTER OF ROME (ITALY).

The outdoor gamma background of the historic center of Rome was studied by in situ measurements and average values of the outcropping geological formations. The survey resulted in two maps of dose equivalent rate, related to pre-anthropic and present conditions. Presently, the average of the dose equivalent rate from outdoor gamma-ray field is equal to 0.31μSvh-1, corresponding to an outdoor annual effective dose equivalent of 0.548mSva-1 and to an outdoor excess lifetime cancer risk [International Commission on Radiological Protection (ICRP). Recommendations of the ICRP, 21, 1/3, Publication 60, 1990] of 2.56×10-3. The originary radioactivity was enhanced by anthropic action up to a level of health risk comparable to that one deriving by fine particulate matter. The assessment of the evolution and dispersion of the outdoor gamma background offers a new perspective to study the urban architectural evolution. Such a mapping allows us to individuate mitigation actions and neighborhoods in which the monitoring of illicit trafficking of radioactive material can be efficiently tested.

Criminal Liability for Illicit Trafficking of Radioactive Materials

The nuclear energy use progressively becomes part of the life of every modern person, who more and more faces radioactive materials in medical institutions, in industry. Half of all electricity generated in Ukraine is generated by nuclear power plants. The peculiarities of the nuclear energy use generate appropriate rules for people dealing with radioactive materials. The article analyzes the standards of the Criminal Code of Ukraine, which provides for liability for acts related to the illegal handling of radioactive materials, for violation of the nuclear and radiation safety rules, violation of radiation safety requirements, the threat of theft of radioactive materials, the illicit manufacturing of a nuclear explosive device, abduction or capture of radioactive materials, attack on radioactive materials transportation means. The grounds and peculiarities for bringing to criminal liability have been reviewed, the range of persons who can be prosecuted has been defined. Conditions and grounds for exemption from criminal liability in the absence of a person's criminal intent to use radioactive material are considered. It has been demonstrated that the Criminal Code of Ukraine, by prohibiting certain actions on the illegal radioactive materials handling, ensures protection of the most important social relations and social benefits.

10B+ZnS(Ag) as an alternative to 3He-based detectors for Radiation Portal Monitors

Typical radiation portal monitor systems, RPM, deployed to detect illicit trafficking of radioactive materials include a set of gamma-ray detectors and neutron detectors. Usually the employed neutron detectors are pressurized 3 He-based neutron detectors tubes. Due the shortage of 3 He reported since 2009, the amount of 3 He available for use in gas proportional counter neutron detectors has become limited, while the demand has significantly increased, especially for homeland security applications. For this reason, many different alternatives are being investigated for its use in RPM systems. The aim of this work is to study a scintillation detector ZnS(Ag) mixed with highly enriched 10 B, 10 B+ZnS(Ag). Using Monte Carlo methods, MCNPX code, the response of two neutron detectors based on 10 B+ZnS(Ag), manufactured by BridgePort Instruments LLC with different geometries, were estimated by calculating the number of 10 B(n,α)7 Li reactions for 29 monoenergetic neutron sources. Measurements and models were made, and both detectors were compared. The importance of the distance with respect to the ground was studied. The response with a 252 Cf moderated neutron source (0.5 cm lead and 2.5 cm polyethylene) was calculated in order to compare with other studied alternatives in the USA by Pacific National Northwest Laboratory, PNNL. With these results we conclude that neutron detectors using 10 B+ZnS(Ag) are an interesting alternative for replacing 3 He detectors. From the analysis with MCNPX we propose an improvement in the detector design.

Detection unit optimization of a neutron searching detector using Monte Carlo Simulations

Abstract The NSD is a portable Neutron Searching Detector developed at Rotem Industries Ltd. with a high efficiency for counting fast and thermal neutrons employing improved gamma rejection. The NSD detection-unit consists of two 3He detectors installed within a polypropylene moderator. The latest international standards for detection of illicit trafficking of radioactive materials require high sensitivity, relatively small dimensions, and light mass. In order for it to meet these standards, the NSD detection-unit was optimized using Monte Carlo N-Particle transport code (MCNP). The moderator mass and dimensions were reduced without deterioration, even improving the instrument's sensitivity. The purposed moderator improvements covered in this paper work well for traditional hand-held neutron search detectors based on 3He tubes as well as for new neutron detection technologies due to the severe worldwide shortage of 3He. Three geometrical moderator configurations were examined using the MCNP code—a rectangular box, a circular cylinder, and an elliptical base cylinder. The optimization results showed that both the rectangular box moderator and the elliptical base cylinder moderators achieve the appropriate sensitivity required by the standards with about 30% reduced mass. A prototype was fabricated with the rectangular box moderator configuration, and its response was successfully validated by comparing empirical measurements against the results of the MCNP code. Performance examination of the optimal detection unit prototype was made regarding the latest international standards. The results showed a 17% improvement in detection limit for radioactive materials along with a 14% to 17% increased neutron detection response, while keeping the false alarm rate below the required threshold, and maintaining a 26% mass reduction.

The Development and Evaluation of Radiological Decontamination Procedures for Documents, Document Inks, and Latent Fingermarks on Porous Surfaces*†

Criminal acts such as an attack utilizing a radiological dispersal device (RDD or dirty bomb), the manufacture of such a device, or the illicit trafficking of radioactive materials would warrant a criminal investigation. This could involve the collection, transportation, and analysis of radiologically contaminated trace evidence. But are law enforcement agencies and forensic scientists capable of dealing with this? This research investigates the decontamination efficacy of two decontamination techniques (chemical and physical) designed for the removal of radiological material from documents of forensic importance. The impact that these procedures have on the development of latent fingermarks and the forensic analysis of the inks on these documents is also studied. It was found that slight changes in the color and chemical composition of a variety of document inks and a destruction of fingermark ridges occurred after chemical decontamination. Physical decontamination had no impact on these parameters.

Dynamic safeguard assessment of terror attacks using system dynamics method for nuclear power plants

For the minimisation of the damage in possible terror attacks on the nuclear power plants and other nuclear facilities, a dynamic assessment is performed in the aspects of nuclear safeguard. The incidents against nuclear facilities are modelled by the time-step scenario. Several cases are explained for the illicit trafficking of radioactive material. The dynamic simulation is examined by the system dynamics method. In the modelling, there are three major models that include the nuclear insider terror, the reaction control and the nuclear forensic steps. The risk increases slowly and decreases rapidly in the result. This is the similar pattern of the September 2001 terror where many lives were lost.

Development of international standards for instrumentation used for detection of illicit trafficking of radioactive material

Subcommittee 45B “Radiation Protection Instrumentation” of the International Electrotechnical Commission (IEC) is charged with the development of international standards for instrumentation used for monitoring of illicit trafficking of radioactive material through international boarders and territories, as well as inside countries. Currently three IEC standards are published. The international participation and the main characteristics of the following three standards are discussed and presented: IEC 62327 “Hand-held Instruments for the Detection and Identification of Radionuclides and Additionally for the Indication of Ambient Dose Equivalent Rate from Photon Radiation”, IEC 62401 “Alarming Personal Radiation Devices for Detection of Illicit Trafficking of Radioactive Material” and IEC 62244 “Installed Radiation Monitors for the Detection of Radioactive and Special Nuclear Materials at National Borders”.

Passive neutron detection for interdiction of nuclear material at borders

Radiation portal monitor systems based upon polyvinyl toluene scintillator gamma-ray detectors and pressurized 3He-based neutron detector tubes have been deployed to detect illicit trafficking in radioactive materials at international border crossings. This paper reviews the neutron detection requirements and capabilities of passive, as opposed to active interrogation, detection systems used for screening of high-volume commerce for illicit sources of radiation at international border crossings. Computational results are given for the impact of cargo materials on neutron spectra, for the response of various detector geometries, the effects of backgrounds including “ship effect” neutrons, and for simulation of a large neutron detection array.

Baseline suppression of vehicle portal monitor gamma count profiles: A characterization study

Radiation portal monitor (RPM) systems based upon polyvinyl toluene scintillator (PVT) gamma-ray detectors have been deployed to detect illicit trafficking in radioactive materials at border crossings. This report sets forth a characterization of the baseline suppression effect in gross-count gamma-ray profiles due to shadow shielding by vehicles entering RPMs. Shadow shielding is of interest because it reduces the alarm sensitivity of RPMs. This observational study investigated three types of PVT-based commercial RPM systems currently deployed at selected ports of entry in terms of spatial effects relative to detector panel positioning. Radiation portal monitor sites were characterized by driver versus passenger side, top versus bottom panel, and narrow lanes versus wide lanes as observed for a large number of vehicles. Each portal site appears to have a distinctive baseline suppression signature, based on percent maximum suppression relative to measured background. Results suggest that alarm algorithms based on gross-counts may be further refined through attention to individual site characteristics. In addition, longer vehicle transit times were often correlated with stronger baseline suppression, suggesting that baseline suppression studies should take transit time into account.

Comparison of nuclear and X-ray techniques for actinide analysis of environmental hot particles

Actinide-containing radioactive hot particles have been dispersed into the environment during atmospheric nuclear tests, accidents of the nuclear fuel cycle and authorized discharges from nuclear reprocessing plants. Several other activities like illicit trafficking of radioactive material or the use of depleted uranium in shielding, weapons can also be considered as possible sources of contamination by actinides. The paper compares detection limits for actinide analysis by nuclear spectroscopy as well as various X-ray micro-fluorescence and absorption techniques using laboratory and synchrotron sources. The detection limits for X-ray techniques were calculated using Monte Carlo simulations. Detection limits obtained for X-ray microanalysis using synchrotron sources were close to that of nuclear analysis. For long half-life nuclides (more than 105 years), X-ray spectrometry was more sensitive, while being non-destructive and offering additional information on oxidation states using X-ray absorption. For U, α spectrometry resulted only in 10−7 g (238U) contrasting 10−13 g obtained for monochromatic beam µ-XRF (micro X-ray fluorescence) at HASYLAB Beamline L. Using the combination of autoradiography and µ-XRF, identification and quantitative analysis of individual radioactive particles of 20 µm diameter were possible. Despite the strong spectral overlap with the Rb-Kα characteristic line, in fluorescence mode µ-XANES (micro X-ray absorption near-edge structure) it was possible to determine the oxidation state of 15 µg g−1 U in a single hot particle.